The big white shell on the beach, tucked just behind a rock, had a long pattern of double tracks leading up to it. Something, perhaps a crab, had crawled into the shell quite recently. Hein, our guide, picked the shell up and tried to blow on the mollusk inside to get it to move, but then he decided not to disturb the occupant and placed the shell carefully back onto the sand.

We were walking on a remote beach on one of the islands in the Myeik Archipelago in the Andaman Sea in southern Burma (also known as Myanmar). Like most of the other 800 uninhabited islands here, the land is made up of thick green jungle, with strips of long golden beaches along the shores. There are no roads to these beaches, no resorts, sun loungers or

We sailed here on a 52-foot catamaran, a small group of travelers lured by the isolation and remoteness of the setting. I was fascinated by stories of tigers and Sea Gypsies that might be on the islands and by the adventure of exploring such a large uninhabited archipelago that has not been tainted by development.

We were spending a week sailing around the islands, exploring empty beaches, swimming, snorkeling and watching the sun rise and set from empty anchorages; the only traffic we saw was the odd passing local squid fishing boat or a dive boat.

Visitor numbers to Burma have been steadily increasing since the tourism boycott was lifted - two of us had just spent two weeks backpacking around Rangoon (also known as Yangon), Mandalay and the north. However, government restrictions still make these islands difficult to access, so being here felt like the ultimate adventure.

We arrived at 115 Island in the late afternoon. It was day three of the trip and not the first island we visited, but it was the first one where we encountered people. Soon after we dropped anchor, two little wooden boats with children in them rowed out to greet us. This was our first encounter with the Moken or Sea Gypsies. The kids were shy, but seemed delighted when our skipper gave them some biscuits and they quickly rowed back to shore.

Moken families

We motored over to the island later in our dinghy, where we met two or three Moken families and saw their spartan camp set out under makeshift wooden shelters under the trees on the beach. The Moken families travel around the islands with a convoy of small wooden boats, staying on one island for up to two months, fishing and diving for sea cucumbers, until the rainy season when they go back to their base at Nyaung Wee. Maung Hein Tun, our Burmese guide, chatted with them and translated a couple of questions for us, but we communicated with them mostly with nods and smiles.

After bidding the Moken farewell, we took a walk through the jungle to the beach on the other side. The rain forest was noisy with insects buzzing and with birdsong, some of it sounding like monkeys laughing. Underfoot, twigs snapped and long vines and plants crossed in front of us as we followed a narrow path through the undergrowth.

"Watch out for prickly branches," warned Hein, waving a stick in front of him in case we walked into any large spiderwebs. The tree canopy was so thick, the branches so interwoven, that sunlight was shut out, and I was afraid to look too closely at the ground in case I saw a snake.

When we arrived on the other side of the island, the empty beach was fringed with turquoise water, with the dry and powdery white sand full of white shells and little white crabs busily scurrying backward and forward. Farther from the shore, tiny balls of sand were arranged in geometric patterns around little holes made by sand crabs.

I realized how alive beaches are when they are undisturbed by mankind, and also, for the first time in my life, in nature, I really thought about Darwin and species and the beginnings of life and how all sense of time can fade away when confronted with a setting as natural as this.

'Everything is alive'

"I love it here. Everything is alive. Every shell is alive," said Michael Forbes, the skipper of our boat, when we were later telling him about the shells. "I have been to the most beautiful beaches in the world, and everything, all the shells, are dead. Here the shells on the beach will run away from you. A guy brought a shell onto the boat recently and it started moving."

When we - seven guests - had arrived two days before on the yacht with its crew of three and a guide, Michael told us we would be going to islands where we would see nobody, where the beaches don't have footprints, where anchorages don't have to be shared. "This is a special place. You are lucky to be here now, right at the beginning. This trip changes people," he said.

The first morning, off the boat's port bow, we saw dolphins jumping and, later, a sea eagle followed behind the boat, eyeing our fishing line. As we approached the first islands, I admired the thick green rain forest with long white strips at the bottom - lines of beach with patches of sand glowing gold in the sun, lit up like the golden pagodas we'd seen all around the country.

The water was blue in places, turquoise in others, and each island densely covered with all types of trees and mangrove swamps. We anchored off a beach to go snorkeling, where we admired parrot fish, domino fish, butterfly fish, snapper, grouper and colorful sea anemones.

We spent the days sailing or motoring between the islands, anchoring at night for sunsets and tucking into curries, tea leaf salad, rice and fish caught that day. The night skies were lit by stars, and there was not a sound as we fell asleep each night, rocked gently by the boat.

Some mornings we saw "symphonies of fish" - a glittering display of small silver sprats jumping into the air, and one day a big sailfish jumped near the starboard bow, its dorsal fin a rainbow of colors. We heard stories about what might be on the islands - like the elephants said to be left on one island when the loggers were arrested. I had read about tigers before I came, and Michael said he once saw a huge print in the sand from some type of large wild cat.

On Swinton Island, we took the dinghy over to the beach and collected firewood for a bonfire and beach barbecue in the evening. It was a bright night with the sky lit by the moon, and after we ate, Michael took us over to a freshwater river and pointed to mud hoppers, a strange, almost translucent, species that looks like a cross between a frog and a fish.

Undiscovered species

Most of these islands in Burma - known as nature's lost kingdom - are unexplored, so nobody knows what species are in the jungle. Scientists believe that they might discover species now that remote parts of Burma such as these are opening up, although access is still limited - very few boats have permits to cruise around these islands (only two yachts and a handful of diving boats), though more permits are expected to be issued next year.

An inhabited island

Later in the week, we visited one of the only inhabited islands, Bo Cho Island, where many Moken are now settled. The long curved beach is lined with palm trees and the shore was full of wooden fishing boats. Behind this is a small village with shops and houses on stilts. Shy at first, the village children swarmed around us, playing and giggling, and held our hands as we walked through the village, leading us up the steps to the temple.

We stocked up on some snacks and headed back to the boat. As we were leaving, and wading out to our dinghy, a small dark-haired Moken girl with white thanaka paste on her face approached me and pressed a shiny white shell into my hand. A parting gift. We exchanged smiles. But this was not just a pretty, empty shell. I could feel by the weight of it that there was something alive inside it. I didn't want to separate it from its home so I discreetly liberated it back onto the sand just before we set off.

Taking the memory was enough.

If you go

GETTING THERE

Boat trips start from Kawthaung in Burma (also known as Myanmar) and, depending on the operator, the meeting point is either Phuket, Thailand, (Intrepid Travel) at the border crossing in Ranong, Thailand, (Burma Boating) or in Kawthaung (Mergui Princess). The Myeik Archipelago is a restricted area and group visas are obtained at the departure point and cost $30 per person. Each cruise has additional Mergui Archipelago National Park/Port fees (check with each operator).

Ranong is a four-hour drive from Phuket International Airport and various airlines fly from San Francisco to Phuket (with stopovers). You can also fly direct to Ranong from Bangkok in Thailand (various airlines).

A return flight from Phuket to San Francisco with Singapore Airlines is from $1,216 including taxes and charges, with one stopover in Singapore. www.singaporeair.com, (800) 742-3333.

A return flight from Phuket to San Francisco with Cathay Pacific is from $1,260 including taxes and charges, with one stopover in Hong Kong. www.cathaypacific.com/us, (800) 233-2742.

A return flight from Phuket to San Francisco with Delta is from $1,739 including taxes and charges, with stopovers in Seoul and Seattle. www.delta.com or (800) 221-1212.

SAILING TRIPS

IntrepidTravel: 201 First St., No. 300, Petaluma. (800) 970-7299. www.intrepidtravel.com. Offers a nine-day Burma Sailing tour around the islands of the Myeik Archipelago from $1,795 including return transport from Phuket to the islands, twin-share cabin on a skippered yacht and most meals. Intrepid can also arrange international flights.

Mergui Princess: Rangoon, Burma. +95 1 401261. www.merguiprincess.com. For a motor (nonsailing) trip, this boat runs snorkeling and kayaking trips in the Mergui Archipelago ranging from three to six days. Prices start from $984 per person (three days, two nights) and include meals.